Molded electrical connection



gir

oct; so, 1956 R. N. FALGE 2,769,157 MOLDED ELEOT'RIOAL CONNECTION Filed Feb. 15! 1952 Cttornegs "JH I "rex United States Patent O MOLDED ELECTRICAL CONNECTION Robert N. Falge, Anderson, Ind., assigner to G eneral Motors Corporation, Detroit, Mich., a corporation of Delaware Application February 15, 1952, Serial No. 271,795! 3 Claims. (Cl. 339-218) This invention relates to electrical connectors. More particularly, this invention relates to connections between an electrical contact member and a conductor wire and to a method for making same.

The conventional method for establishing electrical connections between a Contact member and a Wire leading thereto is to solder, braze or Weld the wire to the Contact. Because such connections are quite cheap and can be made quickly, they have been found suitable for use on high production items such as switches and the like. Soldered, brazed or welded connections are, however, disadvantageous in that they are subject to failure by way of the fact that the bond between the solder and the con tact or the wire can break loose. Even when the metal surfaces are quite clean before soldering, and where the most advantageous soldering operatie-n is practiced, a certain number of failures due to bond breaks will occur, especially where the connections are subjected to constant vibration and shock as is true of switches, etc. used on automotive vehicles.

It is an object of this invention to provide electrical connections which are economical, simple, can be rapidly produced, and which remain quite secure even when subjected to repeated shock and vibration.

Another object is the provision of a method for making electrical connections which is rapid, economical, is suited to mass production methods, and which assures a secure and durable connection.

These objects are carried out in accordance with my invention by exposing one portion of the metal contact to the interior of an insulator cavity, positioning the end of the electrical connecting wire in the cavity adjacent the contact, placing a pellet of a soft, deformable material in the cavity and applying pressure to the pellet to force the soft material against the Contact, the wire and the cavity Walls, so as to secure the wire to the contact, thereby forming the electrical connection.

Other objects and advantages of my invention will appear from the following description and from the accompanying drawings in which Figure 1 is a side view with parts broken away of a switch employing the present invention: Figure 2 is a bottom view of the switch shown in Figure 1, and Figure 3 is a perspective view in section of the electrical connector portion of the switch shown in Figures l and 2.

Referring now to the drawings in more detail, Figure 1 and 2 show an electrical switch of the type used in turn signal devices for automobiles and the like and consists generally of a housing 6 enclosing a movable contact block assembly 7 and a fixed contact plate assembly 8. Actuation of the movable contact block assembly is caused by movement of the arm 9 which extends through a slot in the top of the housing 6. Spaced tabs 10 extend from the housing side walls and are bent over the iixed contact plate assembly 8 to secure it in position on the housing.

The xed contact assembly 8 consists of an insulator 2,769,157 Patented Oct. 30, 1956? ICC plate 11 having a series of through bores 12 in each of which is located a metal contact 13 having a flat head portion 14 abutting the top of the plate 11 and a shank portion 15 which extends through the bore 12. The contacts 13 can be of any suitable metal such, for example, as brass, copper or aluminum. Y

A sheet 16 of insulating material, of about the same thickness as the head portion 14 of the contacts and provided with a series of openings through. which the contact head portions extend, may be provided over the top of the insulator plate 11 to impart a smooth top surface over which the movable contact 17 can ride. The sheet 16 can of course also be integral with the plate 11 so as to provide indentations for reception ofthe contact heads 14.

Each of the bores 12 has a portion of enlarged diameter or cross-sectional area so as to form a cavity 18 open to the under side of the insulator plate as shown and into which the lower portion of the contact shank 15 extends. The end of the contact shank 15 is bifurcated for the reception of the end of an electrical connection wire and the resultant end prongs 19 are bent outwardly to tightly secure the contact 13 in the bore of the insulator plate.

As can be seen in Figures 2 and 3, each of the cavities 18 has a slot provided in one side wall soas to form a laterally extending opening 20 through which a respective i connector wire 21 extends. The end of thewire 21, from which the insulation has been removed, abuts the center of the bifurcated end of the contact shank 15 and is held tightly and securely thereto by the packing`22, which is of some relatively soft, deformable or plastic material which is pressed into the cavity18 so as to lill the crevices formed by the bifurcated end of the contact shank 15. The packing 22 not only serves to give a secure electrical connection but also serves to seal the connection to prevent damage thereto by water, etc.

ln regard to the packing material, while any suitable plastic material will serve we prefer to use an electrical conducting material such as a soft metal or a soft metal alloy in order to better assure a conducting path for the electrical current. When a soft metal such as lead or a lead alloy is used, because of its electrical conducting properties, the current path is complete even though, as might sometime happen in a production operation, the end of the wire 21 fails to contact the shank 15 of the contact member 13.

In order to accomplish the improved electrical connection of this invention the contacts 13 are first secured in the insulator plate bores 12 by bending or turning outwardly the contact shank prongs 19 which are separated by the bifurcation as shown. ln each of the slots 20 is placed a wire 21 so that its end portion, from which the insulation has been removed, is positioned adjacent or against the end of the contact shank 15 and is aligned with the groove which is formed by the bifurcation provided thereon. A pellet, or a number of pellets made of a plastic material and preferably of lead orl lead alloy or some other suitable soft metal, is then placed in the cavity and pressure applied thereto. We have found that a single lead, or lead alloy ball-shaped pellet, gives excellent results. rthe pressure may be applied relatively gradually or may be applied rapidly as, for example, by a blow from a hammer or punch. The pellet must be of a sufficiently soft material to flow into the cavity crevices under the applied pressure without fracturing or deforming the insulated plate 11 and the pressure applied must, of course, be sucient to cause this metal flow.

The plate 11 may be of any suitable insulator material which is suiciently rigid to withstand the pressure ap` plied to the packing and which is su'iciently toughV to;

preclude breaking or cracking during the pellet pressing operation. We have found that nylon is a particularly suitable material for this purpose.

Figure 2 shows a bottom View of the contact plate after the connections have been completed by the pellet pressing operation. the packing 22 is caused to ow into the slots 20 to a small extent by way of the pressure which has been applied thereto, thus giving additional frictional Contact with the wire 21.

The pressed packing 22 is held securely in the cavity not only by frictional engagement with the walls of the cavity, but also because of its having interlocked during the pressing operation with the various crevices, etc. formed by the contact shank and by the end portion of the wire. Thus, a securekand durable electrical connection is attained by a method which is suited to high production.

While the invention has been described in conjunction with a particular switch which utilizes a plurality of electrical connections, it is to be understood that its scope is not limited thereby. The invention can be used for single electrical connections as well as for a plurality. However, we have found that our improved connection is particularly adapted for use on electrical devices which have a plurality or closely adjacent contacts since excellent connections can be obtained thereby without danger of shorting two or more of the contacts as is true when a soldering or brazing method is utilized.

Thus, it is to be understood that forms other than that described might be adopted, all coming within the scope of the claims which follow.

I claim: n

l. An electrical connection comprising an insulator having a bore therethrough, one end of said bore being of enlarged cross-sectional area to form a cavity, an opening in a wall of said cavity, a metal contact member in said bore having a head portion exterior of said insulator and a shank portion extending through the smaller end of said bore and into said cavity, the end of said shank portion having a series of outwardly bent prongs securing It will be noted that a portion 23 of said contact member in said bore, an electrical conductor extending through said opening and into said cavity, and a soft metal packing material in said cavity securing said conductor in said cavity, said packing substantially surrounding said conductor and said contact member.

2. An electrical connection as set forth in claim l in which the insulator is made of nylon and the packing material is selected from a group consisting of lead and the` lead alloys.

3. An electrical connection comprising an insulator member' having a bore therethrough, one end of said bore being ot enlarged cross-sectional area to form a cavity, an opening in a wall of said cavity, a metal contact member having a head portion exterior of said insulator memoer and a shank portion extending through the smaller end of said bore and into said cavity, the end of said shank portion having a plurality of outwardly bent prongs located in said cavity securing said contact member within said bore, an electrical conductor extending through said opening and into said cavity, the end of said conductor abutting said contact member, and a packing of plastic material in said cavity securing said conductor against said contact member, said packing being tightly maintained in said cavity by interlocking engagement with said conductor and said contact member and by frictional engagement with the walls of said cavity.

References Cited in the file of this patent UNITED STATES PATENTS 789,574 Steinberger May 9, 1905 972,267 Shaw Oct. 11, 1910 1,077,746 Peterson Nov. 4, 1913 1,337,329 Schafer Apr. 20, 1920 1,559,668 Brown Nov. 3, 1925 1,684,588 Iansky Sept. 18, 1928 2,078,903 Domack Apr. 27, 1937 2,215,476 Peters Sept. 24, 1940 2,308,638 Balthis et al. Jan. 19, 1943 2,547,932 Downs Apr. 10, 1951 

